Some people want to quit caffeine because they are obsessed with it. Others are told by their doctors to kick the habit.

But quitting isn't easy. It can be so bad, The Early Show consumer correspondent Susan Koeppen reports some people are now going into caffeine rehab.

So is caffeine harmful? And should you quit?

Eighty to 90 percent of people in the United States use caffeine. And that means that millions of them are physically dependent. Yes, you can be addicted to caffeine. And if you try to quit, it can ber very difficult. You can actually suffer withdrawl symptoms similar to those of illegal drugs, like cocaine and heroin.

Tune in Friday morning to find out more as Koeppen talks to addiction expert, Dr. Roland Griffiths at Johns Hopkins Medical Center in Baltimore. He not only studies caffeine addiction, he opened a caffeine addiction clinic.